Axial impact tool and work-retainer combination



p 1961 R. D. DE FRANGESCO 2,999,407

AXIAL IMPACT TOOL AND WORK-RETAINER COMBINATION Filed June 3, 1960 I I0 T u INVENTOR. RALPH D. DE FRANCESCO MZ MM ATTORNEY tates 2,999,407 AXIAL IMPACT TOOL AND W ORK-RETAINER COM$INATION nite I Ralph D. De Frangesco, Chicago, Ill., assignor to Arrow invention relates to percussive tools, and more particularly to a percussive tool such as a riveting hammer and retainer element useful therewith to retain a work member in operative relation with the work-delivering components of the tool structure.

. The usual percussive tool includes a casing providing a longitudinally extending cylinder having a piston or hammer reciprocable therein for transmitting repetitive impact forces to a work member arranged in operative association with the reciprocable hammer. The hammer is ordinarily reciprocated by the alternate -application of compressed air to opposite ends of the cylinder, and the momentum imparted to the hammer during the work-delivering stroke thereof is transmitted to the work member. in a very brief interval when the hammer is in impact engagement therewith either directly or through the intermediate agency of an anvil. As a consequence, the work member is accelerated in this brief interval to a relatively high velocity which tends to drive it forwardly and out of the tool structure unless the work member is constrained against unlimited forward movement. Ordinarily, such constraint is effected by abutment of the work member with the material or devices upon which work is being performed.

At times, however, the tool structure may be inadvertently or otherwise actuated when the work member is not connected or associated with such material or devices, or the work member may deliver a glancing blow thereto; and in either event, the work member would be propelled from the tool structure unlessretainer means are provided in association therewith to prevent such occurrence. In some of the smaller hand-held percusatent sive tools as, for example, a pneumatic riveting hammer, v

Accordingly, an object of the present invention is to provide an improved retainer element which permits ready interchange of work members so that variant forms of work members may be used with one percussive tool, and in which the retainer element functions to constrain each such work member in operative relation with the percussive tool. Another object of the invention is in the provision of a retainer element for use with riveting hammers and similar percussive tools, and which is provided with impact-absorbing and dissipating structure that resistively arrests forward propulsion of a work member tending to propel it forwardly and outwardly of the retainer as a result of impact forces transmitted thereto by the reciprocable hammer of the percussive tool.

Still another object is in the provision of a retainer element of the character described, in which the impactabsorbing and 'dissipatingstructure is in the ,form of an annular band providing a multiplicity of resilient components all of which are operative in substantially simultaneous unison to resistively arrest high velocity forward propulsion of a work member to maintain the same in operative relation with a percussive tool and without damage to the tool, retainer element and the work member. A further object is to provide the combination of a percussive tool, retainer element and work member, and in which the retainer element is resiliently 2,999,407 Patented Sept. 12, 1961 carried by the tool through the agency of an: impactabsorbing and dissipating annular band, and wherein the retainer element is equipped with a second impact absorbing and dissipating annular band adaptedto be struck by an annular flange carried by the work member when the work'member is propelled forwardlyby impact transmitted thereto by the reciprocable hammer of the tool; the two annular bands functioning to absorb and dissipate the high-value momentum of the work.

member to constrain the same inoperative relation with the tool.

Yet a further object is in the provision of a structural composition of the character described, in which each of the annular bands is quickly and easily removed and replaced so as to enable the retainer element to heremoved from the tool and so as to permit work members to be interchanged with or without first removingthe retainer element from such tool. Additional objects and advantages of the invention will become apparent in the course of the following specification.

An embodiment of the invention is illustrated in'the accompanying drawing, in which: I

FIGURE 1 is a broken side view in elevation'of a retainer element, work member and tool composition embodying the invention; FIGURE 2 is a broken'vertical sectional view taken along the line 2-2 of FIGURE 1; FIGURE 3 is a vertical sectional view of the retainer element; 4 isa transverse sectional view of the retainer elementtaken along the plane 4-4 of FIGURE 3; FIGURE 5 is a transverse sectional view of the retainer element taken along the plane 5-5 of FIGURE 3; and FIGURE 6 is a top plan view of the impact absorbing and dissipating band adapted to be engaged by the Work member. With regard to the construction and operating characteristics of the percussive tool, such tool may be conventional and the exemplification thereof in the drawing is a riveting hammer having a casing or barrel 10 provided with an axially extending cylinder 11 in which is mounted a reciprocable hammer or piston 12,. The hammer 12 is reciprocated through its impact and return strokes by, the alternate application of compressed air or other pressure fluid to opposite ends of the cylinder 11 through suitable valve and passage arrangements (not shown). Ihe hammer 12 is adapted to transmit impact forces to a work member 13 either directly or through the intermediate agency of an anvil or tappet, depending upon the particular construction of the tool, and the work member may be a rivet set, chisel, etc. The work member 13 in the specific form shown has a cylindrical upper end portion 14 of reduced diameter that extends into the forward end 'of the cylinder 11 and is axially movable with respect thereto, and at the base of the end portion 14 the work member is equippedwith an outwardly extending annular flange 15 that'is employed in maintaining the work member in operative association with the tool.

Circumjacent the forward end portion of the barrel or casing 10 is a retainer element 16 having a passage 17 extending" axially therethrough. The passage 17 is dimensioned so as to slidably receive the annular retaining flange 15 of the work member so that the work member is axially reciprocable relative to the passage 17. The upper end portion of the passage 17 has a'diametral enlargement, as shown at18, and the dimension thereof is adequate to receive the lower end portion of the casing 10 therein. Intermediate the ends of the enlarged passage portion 18, the retainer element is provided with an annular groove or channel 19 that is disposed in facing relation with a corresponding groove or channel 20 extending circumferentially about the tool casing 10. The

retainer element 16 is provided with a second annula'r channel or groove '21 intermediate the ends of the I smaller-diameter outer end of'the passage 17,-aud it will be noted that the retainer element is provided with a pair of slots.22 and 23 extending through the side wall thereof in respective alignment and communication with the grooves 19 and 21. 'In the'specific'structure such slots "have an arcuate lengthapproximating 90. 5

Mountedwithin'thefacing grooves 19'and20 is an annular band"24in the form ofa fastener'operative to resiliently relate" the tool casing and retainer element 16" and tomount-the latter on thecasing. Suchretainer band isicharacteriz'ed by 'havingimpact-absorbing and dissipating characteristics, as willbe more evident hereinafter. A second" annular band "25 in the form ofan impact receiving element is mounted in the groove 21, and is also'characterized by having impact-absorbing anddissipating' features. The band '25 and-groove 21 receiving the same'therein are disposed forwardly of the work member flange 15, and the band 25 extends laterally inwardly from the cylindrical wall of the passage'17 and 'is'disposed in alignment with and in the-path of movement of the work member flange 15.

'In the specific'form shown, the band 25 has the general form of a helicalspring that is preformed into the annular'co'nfiguration illustrated in FIGURE 6, and therefore the band 25 is provided with a plurality of resilient eoils' oroomponents 26. Atone end, the band 25 is equipped with a type of handle or finger grip'27 which However, upon occasion, the work member may not be firmly seated against the rivet, and a glancing blow is imparted thereto; or if the work member is a chisel, it may cut through the work material before the forward motion of thework member is dissipated .in the cutting operation; and in either event, the work-member would be'prop'elled forwardly and out of the casing and retainer is useful in inserting. the band into and withdrawing it from the groove "21. The band 24 has substantially the same construction 'as" that of the band-'25, but is preformed to a configuration having a slightly Iarger'diameter, and then is provided with a plurality of resilient coils or components 28 and with a handle or finger grip 29. a 7 I In use of the structure, one or the other of several procedures maybe followed in assembling the retainer element 16 and work member 13 inoperative relation with the percussive tool. For example, the retainer element may firstbe secured in position on'the casing 10 and the work member then inserted into the retainer element, or the work member may first be assembled and thereafter the retainer element mounted upon the tool casing. In the-latter'instance, and depending on the particular work member, the band might be placed in position before theretainer element is passed over the work member, or it could be placed in position after the work member and retainer element are in the general relative positions thereof illustrate-din FIGURE 2. In any event, in mounting the retainer on the casing 10, the retainer is telescoped over the forward end of the casing and the grooves 19 and 20 oriented in facing registry. Thereafter, the band '24, and more particularly the end oppositethe grip 29 thereof, is threaded into the aligned grooves 19, and '20 through the slot 22 in the retainer element',-. and' the band is pushed'through the grooves pntil the grip 29 is positioned within the slot 22, at which time the band will have the general orientation illustrated in FIGURE 1. In releasing the retainer element from the casing 10, the band 24 is simply withdrawn from the grooves 19. and 20 by grasping the grip29 and pulling the band outwardly through the slot 22.

In one of the assemblyprocedures set forth, the next step is toinsert the work member 13 in the retainer element 16, and such insertion is continued'until the flange 15- is disposed rearwardly of the channel 21. The band 25 is then inserted into the groove 21 by passing the end of the band opposite the grip 27 through the slot 23 and into the groove. The band is thenthreaded through the groove until the grip 27 isdisposed generally within the slot 23, at which time the band has the general configu- '-ration shown in FIGURE 1. The band 25-may be withdrawn from the groove 21 in an opposite manner to free the work member 13 and thereby permit replacement or interchange thereof withanother work member.

were it not constrainedtherein by some positive means. Also, the tool might be energized inadvertently and be-'.

fore the work member 13 is in proper position, and in such eventsubstantially the entire impact force transmitted thereto by the hammer would appear as forward ly-directed work member momentum whichwould propel it from the casing and retainer at a relatively high velocity.

The band 25 has been found efiective'to absorb and dissipate any such forward momentum of the work member, and to thereby resistively arrest the forward propulsion thereof in a positive manner and without damage to any'of the elements in the structural compositionconsidere'd. Thus, the band 25' provides both the means for retaining the WOlk' member in operative relation 'with the tool, and the means for resistively arresting uncontrolled forward momentum thereof. a result, elongated springs, resilient pads, air cushions, etc. are not required to perform such arresting function's, nor are positive shoulders,.mating surfaces, etc. required in addition to and apart from such prior arresting means for constraining the work member inoperative relation with the tool. YIt'is believed that the plurality of coils or resilient components 26, each of which has a relatively small dimensionin the compressible direction thereof, cooperate one with another, and in an aggregate sense'aiford the high resistive forces necessary to terminate forward propnlsion of the work member without damage to the various components. Additionally, excessively high mo mentum may be partially dissipated in each of the bands 24 and 25 for if an axial displacement tends to be imparted to the retainer element 16 by impact of the work member flange. 15 with the band 25, such displacement will be resistively arrested by the band 24 which has essentially the same construction and characteristics as that of the band 25.

While in the foregoing specification an embodiment of the invention has been set forth in considerable detail for purposes of making an adequate disclosure thereof, it will be apparent to those skilled in the art that numer ous changes maybe made in such details without departing from the spirit and principles of the invention.

" I claim:

1; In combination with a percussive tool comprising a casing provided with a longitudinally extendingtcylinder having a hammer reciprocable therein for transmitting repetitive impact forces to a work member, a retainer element carried by said casing adjacent an end thereof and being provided with a longitudinally extending passage the'rethrough coaxially oriented with respect to said cylinder andextending forwardly thereof, a longitudinally, extending work member supported by said retainer element and having a portionthereof disposed within said passage for limited longitudinal movements with respect thereto and being adapted to have repetitive impact forces transmitted thereto by said hammer, said work member being equipped with a laterally outwardly projecting annular flange positioned within said passage, and an-impact-absorbing. and dissipating structure carried by said-retainer element and extending laterallysinwardly into saidpassage forwardly of and in alignment with. said assent)? flange for resistively arresting forward propulsion of said work member enforced thereon by impact forces transmitted thereto by said hammer.

2. The combination of claim 1, and further comprising fastener structure removably securing said retainer element to said casing.

.3.'The combin-ation of claim 2 in which said fastener structure is resilient and resiliently secures said retainer element to said casing.

4. The combination of claim 3 in which said impactabsorbing and dissipating structure is an annular band disposed circumjacent said work member.

5. In combination with a percussive tool comprising a casing provided with a longitudinally extending cylinder having a hammer reciprocable therein for transmitting repetitive impact forces to a work member, a retainer element carried by said casing adjacent an end thereof and being provided with a longitudinally extending passage therethrough coaxially oriented with respect to said cylinder and extending forwardly thereof, a longitudinally extending work member supported by said retainer element and having a portion thereof disposed within said passage for limited longitudinal movements with respect thereto and being adapted to have repetitive impact forces transmitted thereto by said hammer, said work member being equipped with a laterally outwardly projecting annular flange positioned within said passage, said passage forwardly of said flange being provided with an annular channel coaxial with said work member, and an impact-absorbing and dissipating annular band carried by said retainer element within said channel and extending laterally inwardly therefrom and into said passage forwardly of and in alignment with said flange for resistively arresting forward propulsion of said work member enforced thereon by impact forces transmitted thereto by said hammer.

6. The combination of claim 5, and further comprising fastener structure removably securing said retainer element to said casing.

7. The combination of claim 6 in which said fastener structure is resilient and resiliently secures said retainer element to said casing.

8. The combination of claim in which said annular band is removably carried in said groove and may be selectively removed therefrom to afford insertion and withdrawal of said work member into and from said retainer element.

9. In combination with a percussive tool comprising a casing provided with a longitudinally extending cylinder having a hammer reciprocable therein for transmitting repetitive impact forces to a work member, a retainer element having a longitudinally extending passage therethrough providing an end portion telescopically receiving the forward end portion of said casing therein, an annular retainer band partially disposed between the telescopically related parts of said casing and retainer element and being secured to each to mount said retainer element on said casing, a longitudinally extending work member supported by said retainer element and having a portion thereof disposed within said passage for limited longitudinal movements with respect thereto and being adapted to have repetitive impact forces transmitted thereto by said hammer, said work member beingequipped with a laterally outwardly projecting annular flange positioned within said passage, and an impact-absorbing and dissipating annular band at least partially interposed between said retainer element and work member and being secured to said retainer element forwardly of said flange for resistively arresting forward propulsion of said work member enforced thereon by impact forces transmitted thereto by said hammer.

10. The combination of claim 9 in which said retainer band is characterized by being an impact-absorbing and dissipating band.

11. The "combination of claim 9 in which said retainer,

band is removably secured to said retainer element and casing, and in which said impact absorbing and dissipating band is removably's ecured to'said retainer element.

12. In combination with a percussive tool comprising a casing providedwith a longitudinally extending cylinder having a hammer reciprocable therein for transmitting repetitive impact forces to a Work member and also provided with a circumferential groove extending about the forward end portion thereof, a retainer element having a passage extending longitudinally therethrough providing an end portion telescopically receiving the groove-equipped forward end of said casing therein and providing an annular groove in said passage in aligned registry with said circumferential groove, a resilient retainer band circumjacent said casing and disposed within each of said grooves for mounting said retainer element on said casing, a longitudinally extending work member supported by said retainer element and having a portion thereof disposed within said passage for limited longitudinal movements with respect thereto and be ing adapted to have repetitive impact forces transmitted thereto by said hammer, said work member being equipped with a laterally and outwardly projecting annular flange positioned within said passage, said retainer element being provided with a channel circumjacent said work member forwardly of said flange, and an impactabsorbing and dissipating annular band mounted within said channel and extending laterally inwardly into said passage forwardly of and in alignment with said flange for resistively arresting forward propulsion of said work member enforced thereon by impact forces transmitted thereto by said hammer.

13. The combination of claim 12 in which each of said bands comprises a helical spring.

14. The combination of claim 12 in which each of said bands is removably carried by said retainer element, and in which said retainer element is provided with a pair of slots respectively aligned with said circumjacent groove and channel and communicating therewith, said bands being removable from and insertable into the respectively associated groove and channel through said s ots.

15. A retainer element adapted for use with a percussive tool comprising a casing having a circumferential groove about the forward end portion thereof and provided with a longitudinally extending cylinder having a hammer reciprocable therein for transmitting repetitive impact forces to a work member and comprising also a work member equipped with a laterally and outwardly projecting annular flange, said retainer element having a longitudinally extending passage therethrough enlarged at one end to telescopically receive the groove-equipped forward end portion of such percussive tool therein and providing in said enlarged portion of said passage an annular groove adapted to register with the circumferential groove in said tool casing, the other end portion of said passage being adapted to slidably receive the flange of.

such work member therein and being provided with an annular channel normally disposed forwardly of such flange, said retainer element having a pair of angularly extending slots respectively aligned with and communicating with said annular groove and channel, and a pair of annular bands for respective disposition within said annular groove and channel and being insertable into and removable therefrom through the respectively associated slots, at least the band for disposition in said channel being a resilient impact-absorbing and dissipating member for resistively arresting forward propulsion of such work member by abutment with the flange thereof.

16. The retainer element of claim 15 in which each 

